Fig. 3.

Integrins mediate VTN-induced LIF and IL-6 in C6 cells. C6 cells were seeded onto plastic for 24 h in serum-containing medium, then serum starved for 24 h before addition of VTN to the medium for 4 h. Co-treatment with RGD or αvβ3 (P11) integrin-blocking peptides reduced the effects of VTN on LIF (A) and IL-6 (B) mRNA expression. RAD is a non-RGD control peptide. LIF and IL-6 expression were not completely abolished in these experiments, suggesting that there is an additional VTN-activated mechanism. Indeed, BC-11, a uPA–uPAR inhibitor, decreased VTN-induced LIF (C) and IL-6 (D) mRNA expression, but did not have any effect alone, after 4 h. Data are means±s.e.m. of four independent experiments. Since 1 µg/ml VTN was effective in inducing LIF and IL-6, we only chose this dosage for these experiments. Co-incubation of both P11 and BC-11 could not further decrease the VTN-mediated LIF and IL-6 induction. Finally, knockdown of uPAR by means of siRNA (siUPAR) reduced by LIF (E) and IL-6 (F) induction by VTN (10 µg/ml). uPAR knockdown was confirmed by RT-qPCR (G, n=3). *P<0.05, **P<0.01, ***P<0.001.